A known electric powered pump unitarily includes a hydraulic pressure pump, an electric motor for driving the hydraulic pump, and a driver unitarily provided on the electric powered motor for controlling the driving electric current applied to the electric powered motor has been developed. With the known electric powered pump described in Japanese Patent Laid-Open Publication No. 2000-018173, the driver is provided between the hydraulic pump and the electric powered motor and the communication between the suction passage of the hydraulic pump and a discharge chamber is established by bypassing the part of a suction passage via the driver, an electric powered motor portion, and a bearing portion in order for circulating the operational fluid adjacent to the driver to cool the driver corresponding to a heat generating portion.
The small size electric powered pump likewise the known electric powered pump is used as an auxiliary pump, for example, as a pressure supply source to a clutch in a transmission at the engine stop state of a hybrid vehicle including an internal combustion engine and a motor generator and as a supply source for a cooling oil of a motor generator for the electric vehicle and the hybrid vehicle, or the like.
In this case, the high heat radiation is required for the electric powered pump because the electric powered pump is positioned on or adjacent to the motor generator generating the heat and the transmission in the high temperature engine room. Further, with the electric powered pump with the unitarily provided driver, the heat radiation is required to be increased further because the driver per se generates the heat.
With the construction of the known electric powered pump described in Japanese Patent Laid-Open Publication No. 2000-018173, a portion of the operational fluid is circulated adjacent to the driver using the hydraulic pressure pump to cool the driver, which does not achieve the sufficient cooling effect when the temperature of the operational fluid is high.
Further, because the transmission provided with the electric powered pump and the motor generator are vibrated, the construction to restrain the vibration of the driver is required in order to prevent the damage and the detachment of the electronic parts of the driver due to the vibration.
A need thus exists for providing an electric powered pump, which achieves the high heat radiation and restrains the vibration of the driver.